Black-naped Tern ©Kenneth Lam

 

Common Name: Black-naped Tern

Scientific Name: Sterna sumatrana

Local names: 黑枕燕鸥 (Simplified Chinese), 黑枕燕鷗 (traditional Chinese), 엘리 그로 제비갈매기 (Korean), エリグロアジサシ(Japanese), Dara laut Tengkuk Hitam (Indonesian), Camar Tengkuk Hitam (Malayu), Nhàn Sumatra (Vietnamese), นกนางนวลแกลบท้ายทอยดำ (Thai).

IUCN status: Least Concern

The Black-naped Tern is a small to medium-sized tern species, distributed mainly in Tropical Indian and Pacific Oceans. It has distinctive for its white plumage except with a black band from the eyes, which continues in broadening to the nape. It contains two subspecies: S.s. sumatrana and S.s. mathewsi.

 

 

Identification

Adult Black-naped Tern in Hong Kong ©Kenneth Lam

  • Size: 30-35 cm; wingspan 61-66 cm.
  • Breeding plumage:
    • White body
    • a distinctive black band from the eyes, continues in broadening to the nape
  • Non-breeding plumage:
    • Only the black band becomes paler and less defined
  • Juveniles have a dusky cap but leave a white forehead, creating a masked look; upperwings heavily scaled with creamy edges.
  • Beak: black
  • Legs: black

Distribution range

The subspecies S.s. sumatrana in EAA Flyway region breeds Eastern to Southern Japan, China, then migrate to the south. Others resident or disperse locally in Malaysia, the Philippines, Indonesia and New Guinea, to Northeast and Eastern Australia and Pacific Southwest Pacific Islands.

Habitat

  • Breeding habitat

Sand or coral islands, reeds, sand spits and rocky cays.

 

Breeding habitat of Black-naped Tern in Hong Kong ©Kenneth Lam

  • Non-breeding habitat

Feeds in lagoons and close inshore over breakers, sometimes at sea.

Behavior

Black-naped Tern feeds on small fish and almost always forages singly by shallow plunge-diving or surface diving. Breeding colonies are small, and usually consist of 5-20 pairs but can be up to 200 pairs.

Population estimate

The global population has not been quantified.

Main threats

  • Human disturbance
  • Invasive non-native/alien species/diseases

Natural threats

  • Flooding

Conservation Work

Conservation research of breeding terns in Hong Kong

 The Agriculture, Fisheries and Conservation Department (AFCD) of the Hong Kong Government and Hong Kong Bird Watching Society started conservation research on breeding terns in Hong Kong waters in 2018, with support from the Japan Fund for Global Environment (JFGE). The three species of terns breed in Hong Kong are Black-naped, Bridled and Roseate Terns. The flagged terns have the white flag on the right tibia and an engraved yellow flag on the right tarsus (see photo). (Read more: link)

A flagged Black-naped Tern in Hong Kong ©Agriculture, Fisheries and Conservation Department (AFCD), HKSAR

Fun Fact

When facing predators, adults mob predators and may give plover-like “ungulate” displays with upright posture and spread wings to frighten the predators away.

References 

Projects on conserving breeding terns in Hong Kong: